1. Field of the Invention
The present invention relates to a motive-force transmission changeover mechanism in a disc apparatus of the type having a disc carrying tray to carry a disc for loading and unloading in which a single motor is used for driving the tray, the raising and lowering of the traverse unit, and the forward and backward movements of the optical pickup.
2. Related Art
The principal movements in such type of disc apparatus include: turning the turntable; moving the optical pickup for recording and/or reproducing sound and/or pictures from the disc; moving the disc carrying tray between the projecting position in which the disc can be put on or removed from the tray and the withdrawing position in which the disc can be put on or removed from the turntable; and inclining the traverse unit to prevent the advancing disc from hitting the traverse unit, which otherwise, would remain in the way to the loading position.
JP2000-222803(A) shows an Optical Disc Apparatus which is so designed that the number of the drive motors allotted to the above described different modes of operation is reduced to minimum. Specifically the proposed Optical Disc Apparatus uses a first drive motor for rotating the turntable and a second drive motor capable of: rotating in opposite directions for moving back and forth the pickup across the disc; raising and lowering the traverse unit and moving back and forth the disc-carrying tray. The Optical Disc Apparatus is equipped with a motive-force transmission changeover mechanism to change over the driving force of the second motor between the tray driving mechanism and the pickup driving mechanism. The motive-force transmission changeover mechanism is built in the mechanism for raising and lowering the traverse unit.
The motive-force transmission changeover mechanism comprises a changeover rack and cam slot formed on the traverse rack, a trigger lever rotatably fixed to the traverse chassis, a lock lever slidably fitted in the cam slot of the traverse rack, and other associated parts. Further it comprises a cam gear having a cam slot made on its circumference for raising and lowering the front end of the traverse unit. The cam gear is meshed with the last one of a gang of gear wheels, which timely conveys the driving force from the second motor to the tray driving mechanism, the traverse unit inclining mechanism or the pickup driving mechanism. Thus, the single motor can be used in effecting movement of the optical pickup, inclination of the traverse unit and reciprocation of the disc-carrying tray.
However, the parts such as the trigger lever having changeover rack and gear portion, the lock lever, cam gear having a portion lacking teeth and the like to make up the motive-force transmission changeover mechanism are complicated in shape, and the assembly of such complicated parts often cannot work well because they are difficult to work together toward their timely cooperation, e.g. an engaging timing between the changeover rack and the trigger lever; a timing for the trigger lever to rotate the cam gear. As a matter of fact, such motive-force transmission changeover mechanism is hardly reliable in operation.
To assure that the prior art motive-force transmission changeover mechanism works reliably, such complicated parts need to be made with extreme precision, and the so made parts need to be arranged and placed relative to each other with as high precision as are required in making them. Also disadvantageously the metal molds for producing such precision parts are very expensive, and extra spaces are required for some separate parts such as the trigger lever and lock lever, not allowing reduction of the whole size of the disc apparatus so far.
In view of the above one object of the present invention is to provide an improved motive-force transmission changeover mechanism for use in a disc apparatus capable of working together in unison by a single motor, the parts of the motive-force transmission changeover mechanism being simple, well timed and reliable of the transmission changeover, and the size can be reduced.